In a medical circuit used for infusion, transfusion, nutritive dose or the like, connection and detachment of circuit parts may be carried out for sustained or temporary flows of a plurality of fluids such as medicines, blood, fluid diet, etc. It is well known that the circuit is fitted with a connector or connectors for this purpose.
A representative example of such connectors is a three-way cock. The three-way cock is composed of one male-type lure connector and two female-type lure connectors, and connection of circuit parts is carried out by fitting of the lure connectors. In this case, when a circuit part is detached, a portion serving as a fluid passage is exposed to the outside air, leading to poor resistance to contamination with bacteria. Particularly, the female-side connecting sections tend to be subjected repeatedly to connection and detachment, so that they are frequently exposed to the outside air.
In view of this problem, there has been a connector in which the female-side connecting port is equipped with a valve disk (valve element) for restraining the exposure to the outside air of the portion, serving as a fluid passage, of the female-side connecting port. In such a connector, the fluid passage is opened by piercing a vale body disk a needle or by inserting a male-type connector into a slitted valve disk; therefore, after the detachment of the needle or the male-type connector, the valve disk is again closed, whereby the fluid passage can be prevented from exposure to the outside air.
In these connectors, however, the valve disk is provided for the female-side connecting port on one side only. Therefore, when the male-type connector is detached from the female-side connecting port on the other side, the female-side connecting port would be exposed to the atmospheric air.
Besides, these connectors have drawbacks in that it is difficult to achieve good flow of the whole amount of a liquid medicine due to the presence of stagnation areas in the female-side connecting ports or that the presence of the stagnation areas would lead to an environment where propagation of bacteria is liable to occur. In addition, there has been the problem that while the interior of the connector is filled up with a fluid such as a liquid medicine prior to use thereof, it is difficult to deaerate the connector interior.
Furthermore, there has been the problem that the capacity of the connector is liable to change at the time of attaching or detaching a needle or a male-type connector to or from the female-side connecting port. For example, when the capacity of the connector is increased upon detachment of the male-type connector, blood is caused to flow backward from a blood vessel catheter connected to the connector into a catheter, which would cause closure of the blood vessel catheter.